This image shows a variety of supplies, including foil, plastic wrap, scissors, a bowl, a thermometer, and tape. The text reads, "Solar Ovens: Reflectivity and Insulation."

Variables that affect solar oven efficiency

So you’re building a solar oven? 

Solar ovens are a great DIY project! You can create an effective cooking device cheaply from household items. Also, solar ovens use renewable energy from the Sun, which is good for our environment. You’ll learn many important science concepts and develop your engineering skills through the design and building process.

However, you might be wondering:

  • “How can I make a solar oven that actually works?”
  • “What factors will influence the performance of a solar oven?”
  • Or “How can I make my solar oven more efficient?”

There are many factors that can affect how well your solar oven heats up, including box size, reflectivity, insulation, and moisture (Aalaff, n.d.). This post will focus on how you can use reflectivity and insulation to improve your DIY solar oven’s efficiency.

Reflectors to improve solar oven efficiency

This image shows a box with a bowl in the middle. Both the box and the bowl are lined with shiny foil.
This solar oven box uses foil to increase its reflectivity.

In general, the more solar energy that is directed toward the cooking surface in your solar oven, the hotter temperatures you’ll be able to reach. You can get some sunlight to enter your solar oven by cutting a hole in the box and making a transparent “window” that sunlight travels through. However, you can direct additional solar energy toward the cooking surface by using reflective materials, such as aluminum foil or mirrors (Aalaff, n.d.).

When light rays hit a reflective surface, such as aluminum foil or a mirror, they bounce off in another direction. If a surface is smooth, then the light rays will be reflected in the same direction (Brittanica Kids, 2022). Reflective surfaces can be used to transfer light energy from place to place.

A solar oven can use reflective surfaces to direct additional solar energy toward the cooking surface. The more energy that is reflected toward the food, the hotter it will get.

Insulation to improve solar oven efficiency

This image shows a box being converted into a solar cooker. It is lined with white paper insulation to reduce heat transfer and improve the solar oven efficiency.
This solar oven box was lined with insulation to reduce heat transfer.

Another way you can improve your solar oven’s efficiency is through insulation. Now that you have solar energy entering the box and heating things up, you want to trap the thermal energy. Trapped thermal energy will cause an increase in temperature. Whereas, if the thermal energy is leaking to the outside environment, the temperature inside your box won’t increase as much (Aalaff, n.d.).

Thermal insulators are materials that prevent heat from passing through easily. Most often insulating materials work by trapping gas like air.  Because the particles in a gas are far apart, they don’t bump into each other often, and therefore, don’t transfer thermal energy as easily as solid materials. Feathers, cotton balls, newspapers, and packing peanuts are all examples of insulating materials.

Layer insulating materials inside your oven to trap thermal energy and improve the efficiency of your DIY solar cooker.

Time to cook!

As you begin designing and building your solar oven, consider how you are using reflective and insulating materials to make your oven as efficient as possible.

Works Cited

Aalaff, M. (n.d.). Solar cooker design and construction guide. Natural Building Colloquium. Retrieved November 13, 2022 from http://www.networkearth.org/naturalbuilding/cookers.html

CK-12 Foundation. (2022). Thermal conductors and insulators. CK-12. Retrieved November 13, 2022 from https://www.ck12.org/physics/thermal-conductors-and-insulators/lesson/Thermal-Conductors-and-Insulators-MS-PS/?referrer=concept_details

Encyclopedia Brittanica. (2022). Optics. Brittanica Kids. Retrieved November 13, 2022 from https://kids.britannica.com/kids/article/optics/390822

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